SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c90f228ee4ba5db0006d92fe8897f12c130be526c378b5d5dad59face0d4d15' 
  AND token = 'aWPqUxCMMkDBwngZfnwDNjXnTklbCC+rlFFeZI1PjvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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