SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92452b8db54baf74dd2b73d1efd42a298e07e478ecd210be4e17030447c39bd5' 
  AND token = 'B3144ZR1RtWyU4X3lpxd1pLW2tYFtjCbFWEtAxTHax4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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