SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '734da2e99874a2467a83806bf4e71dc409aed620fb579d27bc791283a0220091' 
  AND token = '4sZKMZJhh8t/34CSjWKXvvqqGzQfoS32SDxkatNh8+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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