SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1d420a4443a99c9ec20ddc160a33d3e8433f3d33f772ecdb9bb28b6d13a6f6e' 
  AND token = 'kpYmKjhEQvYj8NL1ybd4Bxo7rQRAzYOCbC/e7ER+9kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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