SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b140163aacd6d4c79685aa15350b7a90bb4dc4d668ef005c82660d764a20942' 
  AND token = '/prZeWryiWkZ01r2LOhsbZ31VPPdGm7cQjOYdkAdL8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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