SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c399809a46b6a9a5e3afd134bc7e8aeb5b8d3e9fb948565d5c1abd5da8018060' 
  AND token = 'w4dshhvFXq6pCWyBfOylByPPx2pg2KhZ5Qqohhrq4ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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