SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9866e70d33517eec98850117f41d6aa080924a1082b08353a30fdba589fe249' 
  AND token = 'Ohv+yt56BNjpTeWIpgPyj+ET/EEYolphNkj3LGTat+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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