SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce717d7f0d98ca9a11f95cefa7278cabb6f4f72ba7b8203de697914e51053564' 
  AND token = 'uhg0S2uxYWT8Xz2k3WmyzCFuKviJvbdZRkt+GUoVVk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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