SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '359d4a9bc2cb899b4d055bae19d3e899b1e1007f700313bbd24d19871c7f317d' 
  AND token = '6jlbvOms3jswuz/iemKYGhPDavbVwku7pnAB4wUzjJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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