SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f03a21944143e565f86f599e466081a33335b43ef5500b576eb1a9850b46d18' 
  AND token = 'UfiXkfhW2SttZLImZYlrgqbjrPOEOA198t6j978tKZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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