SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '114b1e17e9dd021f1d0af2d5ddfc3949fcfda48cdedbf970f3efd1864c1c721c' 
  AND token = 'Uk/UkFFd8vIDdHdx8sPNkEeIOcHufBD80CzUEKDOXHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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