SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0a0d6d4115fce578656d91b73cb6b136c921f51113f1fd0af5d866c2a632b5' 
  AND token = '1J5aElWkHujPOj5hMtLCnNZWbnbUh1IlbmI16A+X438=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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