SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb636b0d5d399fe361d0320740e32a46f750ad7992405a237557a71ba94b8e8b' 
  AND token = 'm0rPUO5hXzH/0hQoVWEGCzcVqvSoBtlxKFWY3+riWl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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