SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf2fe71de31d75acfb5023788d0052e1c2640480f9c59fcb2816cb6232862f5b' 
  AND token = 'xG8byu+srCtUqyCHTXCWwlV1vxjew7gvTyN39yP3FZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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