SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0c35be520a18c8fe069d13a1c7ca39bfa4e5f1ddd397bbb01173255de52adf7' 
  AND token = 'JwPqKUL24Lvl7ZlCX6qgjF62HaYwK7ZQkOXTdqFZwDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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