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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c66f4ed8e8ea27c5e8703829b6f0f28d43b850a929fb1986d3da3c14bd0cdddd' 
  AND token = 'LJUc6lxcDptjYLYVgUnd49sT0lx7U41Q25xNNpzDSI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}