SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e1572b12a05b6fe8157a4683148f08a38cb745d5ecc9674a9615dd7a9413434' 
  AND token = '4NKP4WIm4G6JFyTsi4tgxB3OAC0AwajUo4K9LMC9V3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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