SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bc3a15a4c30ad0ebd72172f5348d98701e1c02a3fa2bca5c63e4163b00cf67a' 
  AND token = 'wBzmAEiieWxPxmp4K34DOJmXyRWmXMUXA6662JYBNIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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