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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e3dd5dfcedbb23084df9a2c2574db0d38de8785c03fbe6d3fc8e80abe4e644f' 
  AND token = 'cCwNn+ZJJYDHNe8pNKXDcpuplzhpKaH7xj8DR/ClarY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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