SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96512b6589a3f103f48425190c7c726a0d68c03c3d78d7b6d7f1a76309df1e0a' 
  AND token = 'UYUkE+Zg+d04cTKoxNBaePBv6iGuLlAZFbJy+JeIz3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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