SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13d841eb7185718603a9065595a738864a09bdf77c0b2093ed8439e5760b211d' 
  AND token = 'i9jkJUn/M3gfDY0uhyNnbVIkx1dwW+mHHnrXb97y92I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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