SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90dea92ca963463c0f86ee46948b7eb1dd2fa64971f0cd35e73b8b8d702ac0e5' 
  AND token = '5/p4S57SSU4Y5/WGInhRr+VKVo+6+WOBaKfrYQBFUTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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