SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64a51d58a50e365c90ccc80b127c395596d88d47df3fedba789542cde1a6aa90' 
  AND token = '3nICy89/nrVPFBO3oW8oERLOqfCAmJnVcil3XQz6AjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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