SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7eac7c730ce9e6e4bde6c876b0f40ff517013566f31657054d78091ad75a6cc' 
  AND token = 'dvDWxznQVbySendM+nPELxmjFLkN8ifbMngYWnlsZH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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