SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50dcd5a31a80ca5d37ecec6532979a74a553285199d4f24004f7eb66f19189e' 
  AND token = '8HkDlOfQNiVfpoA+DSrCFapcqYZQPyIKcM7tpP0lI90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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