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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f785e50f2f8d9960c5ebe3267c64d18c03a318f6afde96b760ba7c1cb1396d8' 
  AND token = 'mr1n2d5/JMBQ9xiSGr4/aXPg/6NqXKdOZQH/46Qvik4=' 
  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"
    }
  }
}