SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ced4fa1bf6794d0704e4acc6c77d14b528e4d877cf1a213f6b823a72615592' 
  AND token = '+0lXj/HthNiwJ/xCoVMG1XWkWPv0T4exzB94AznTw0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}