SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd434d7658819a3ec8d608a60d22fd05dfc723d7924f731f3860f79e8e0bed15' 
  AND token = 'uXqIMBCTF5re3qGIiIKZGtzgUwaM6inyW1u1V6AVYn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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