SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '510ad4e8a9eece3cecc95e36e211908ef1897261926725cfa661aa62521798de' 
  AND token = 'DnBjzp79tjh+71ON4We3y+QNMfXOeHMrvLYOG+MUvJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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