SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9297c5146cbd932032aebfd895157b01b13eee8075be1363bff75d7682564ce' 
  AND token = 'pGNr/uOstp5qwqQrxk7jGfMlZMWfnQCjmKdeFhPn1MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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