SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a11eda61cfadc1bd49710debaaf490d5e256442898390a1d0587e1a0c3ffeef4' 
  AND token = 'DM/BpE7lJe7dftIs5wiQklGyCqhtpOaugZe+iWHUYsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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