SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c29665af5f27d7dea3ec5b29bf807fceee9988b2ee7c6a9ba586b0a6db8901f8' 
  AND token = '9540ac3X/lYTNgzJUKaCoknnwihxB23ku7S30Gy3f6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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