SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8346e5f8a0b5271ca19ce895d4542ad36afa36ed2673ecd9cddfa43b9c823664' 
  AND token = 'M35vhMGB89bYl2C869hrOle+WWYmQY78kaA+drkDq84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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