SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2c52a9f1244841184b7b92f026565120bf5ad7cbf4cf8db2fd8510a30aa5b81' 
  AND token = 'ojUZgcICgBJvTNLE8aBkgxx3uN97C/JKxCSEj+WDi/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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