SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c96765d8716f9afcceca06f5371a011645391384d1c231f1cd676e0bac643c76' 
  AND token = 'jTfl37dq+ynZBKAhKul4aDJTPAkDCtzXy0NnoCl5MWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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