SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79f840ed5b71b1f31011c4ab75727b7c894ba6dfb5219f0552a4e21dddb2f9e0' 
  AND token = 'cRkFVR+6kx3LZ6WBCZNdKOs3XIVrNxjXByvXgPxGH6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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