SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c761be648bb78989d0f55ca1014009a33d9343a088506542486ffff44177daf' 
  AND token = 'tidNuS1fswSqGHtHES11jdSeE9J82hDYxbAvBRDhZtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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