SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5818c9bf12df35491163f4a8451fd6289a16c6b0cd309621eae6684a039d32b' 
  AND token = 'ZtlZxiHeKgZ3uOPNsNLeVkVAbXn64A7r/dLS64AOFpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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