SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '733cf6e356494077688046db69d28f9eff8de514f1be7e932780f813af93ea24' 
  AND token = 'i0JV1r3GINs1R5j9/5eNCoqtEttz3udkYRjlUJxlQ1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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