SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a108520e243c77ffe92866c644a1809b73ad6cae5789c61ddafd3ece0584ed17' 
  AND token = 'DIPljjmGmp9J58fiDTTWTP+qtNTx474304/xSYWn1G4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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