SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66e2715cac3a4c04d224f8bdc96d5582e6da5490f2e6420b760354c5ccce4374' 
  AND token = 'u/Nj3SZpUzgdfXK3ZZX1eAfhBTCQY8CEQjMskLFzhWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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