SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f859da564c972703ff50cbc7234400805881a3f90651456c5f50b4062fc4df35' 
  AND token = 'bMZWvZRYsLdWGaNaezUPDObZ2lax0S8FxT+zDLbhA1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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