SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79efe5d8bf65b9640419f4bad0e6b82279d99bf737f011c923249a0da4a0c0fa' 
  AND token = 'mdjbmt47kdi1IZZ1zuUXGxJvlhgvA+Lc5V3nqz2NDvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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