SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af0d9b5a1d45557d9c99eceebb1b71bc13049c60c7e8ddfe582e34ee31738ee4' 
  AND token = 'F661yd3tMKAEwsD/rcZ4d1axMyrJm+FsERC2toipvFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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