SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eaa1d5a1a5421d6b736115a2adda8562280ec5e6a8cb24cfc4a1fb2619e5d9f' 
  AND token = 'CZJSrzalr54BEIxFI9O7OvnyIgCQTBGhnyUCzgdJLQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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