SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '470e7bcf43e829e3bf11cb5215cba50a4b83d9c97d407a666148ced8421a3132' 
  AND token = 'B1enny6+tePfQFPY7zj6W2nWXctsACy/VLSWQnHjW14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}