SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd471effc6096d1b28575982641c0b510a1d6a2a9470f09ebd4116eea32152814' 
  AND token = 'sIOUB4CSCDYLhSkRPVJaiHMAB7oKXKzjQC9tp9nlUAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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