SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339d23eb88bba7960eb59415f5169673763b5dfa1236f7418bd9c028f0c1856d' 
  AND token = 'PxqQgkdZ1jt+KpWk0yrX49t6NTIpwMloQU1KqwiptRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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