SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7515c84765996170f4302b088d0a03d343e46539be534232991c23d5c9647d2' 
  AND token = 'EzoCwizdHQWpGj01sa6fYx1F5r1OkWArU5Axpav1KOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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