SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '390bb73921e34510d317acffce49e374f349535f3af4941a650f3ed26caaab49' 
  AND token = 'Yn2bzBz3xAoq84ZNKg314pU+NEeTrReU4X38RoDaaRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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