SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6f19640e57bfe89119f2654a3474b528956518b3b85f731327ef4121cc75d7a' 
  AND token = 'bMlEeQYDYyGe0HDXwZV2GoRBje8fyHqQJ8ahxZYtwx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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