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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d9a0e38e0daf0744b6d796a1d008a31de4e98092f3f73fdeca3c9aefa66851a' 
  AND token = 'N1rf1uBbDDvkaiExYSVn+JEOCVoPWD8Okw6y9lseryA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}