SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6014a4797271c03332a3c9f0b24bc9b31e27b7ff8a08dd29c44db3da052631df' 
  AND token = 'g83v1llq8VTF4VdYNoaQ/HbsIMyiimTxoPgNi/p3820=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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