SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9f529a91f1873af1983affaef4318037c5b008c9981a36770ed4fa5fd755655' 
  AND token = 'kU27Ej8BNA1eLk3B6cr8y4lflYsljN7xHfXVU+zBoY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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