SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe9dcb389018ea125650919fbf85b6362f773dda04e46a38aeb6eb50263195a' 
  AND token = 'KeeLrY1gr2nz6wKFZqI+kseiBHdYmrUniS6Uc1oW4No=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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