SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af8abbd77cdb290f8c3d1494f4237296549edd2d0c885f91c74681f0bbdaa5f6' 
  AND token = 'G0zWRMiUHQEwro3QZ/Dn287yUpj/KYmWK+OnbOFDNUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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