SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae3ccd9b3619e43956281e40037837831bfae933c2d17e53b0cf9ddb53ade0af' 
  AND token = 'IjREvSwbqH7UaPWDM4Aq1AiL/849wRcE9rJscitxAK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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