SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c21d9b5073d26cc0345d96076c2040ea83c4e5df4913f6283b7f0413c99af96' 
  AND token = 'IlwRFAA51zPdfCLwXbEoWQthpnLJRK8NrmyuF7i+w0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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