SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bed232a90f4f5ee1c4bc4a061395a235e721b72eebf438ac06a9406027bc31d' 
  AND token = 'ubEz0EfUeIhPjyPgGWDSjhcTrpqIH8y4viGyJaszRdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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