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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5752efe454e3c5a9270516049f6c21a49aa7f78325b0050b32fc0a6068bd24c2' 
  AND token = 'W5oQBV1qjiQBQ5/cIAEy+1e8mO1dGROxE/nQ60qvy2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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