SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abd52dec40038c144a53d242290a391470fa7dbe17093875fc3fdd544aa96891' 
  AND token = 'xg+QszPBcnHHVURmopfzlCiySWU6/V7ZCym8xbkj9vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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