SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6915891e7e65a0534ebdb9997416f9063fd3ac89f8d745d4711ead0f53698468' 
  AND token = '6lDUdVSzpdgxzHp2+fBhXyT5yC5aqm2oOwKMO5Lgj+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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