SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e42ffb8c5809deeb53a61fcf9808956265648d2d092af8029b8e7b223b10879d' 
  AND token = 'yYZNh7rFxVWYZD+iDQ2iErfHsXCO6ejB6mzCvHHFlrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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