SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ba0fd644fabd51b38261275ddce856fb09295aebf938928cf5589f55472d41c' 
  AND token = 'cCnczm/ZWEZHOxgI9+NOp1jqU4PXhLw2qOE37HCcCc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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