SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f951ab15f5c717ae25d11af07d1623ffca6163f2fc6e68b4a02e75070e892758' 
  AND token = 'pU9hRzbmc3Y1Duvus2sWwA/K7i/qxIMQ2GCAZQxqAIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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