SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57fcd41b2f85e997dd2efdc04e114ea0aea5391d0ee5251ea6047aaadbd0aa8c' 
  AND token = 'crUCrMrGCYF1XXWK7NnxluLODMtcHsduvWQ1c+Wx4mY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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